Generally Chest freezers have a freezer compartment defined by an inner case surrounded by insulation which is cased by an outer case. The cooling system is normally static with a cooling circuit comprising a condenser, a compressor and an evaporator providing cooling energy to the compartment. In static systems the evaporator has a large surface in direct or indirect contact with the chest freezer compartment. Direct contact means that the evaporator is positioned on the inner case inside the compartment, with cooling agent tubes providing agent to the evaporator from the closed cooling system.
Indirect contact is normally used in Chest freezers. In such freezers the evaporator consist in a meandering tube extending between the inner and outer case. In order to achieve a good heat transfer between the evaporator and the compartment, the inner case in normally made in a metal, such as aluminum. The evaporator tube is then placed in contact with the inner case in order to transfer cooling energy from said tube to said case. The cooling energy is further transferred from the inner case to the compartment. Normally the evaporator is placed in contact with the inner casing at its floor side and all four sidewalls.
The Chest freezer compartment is normally enclosed by a door or lid enclosing the compartment opening facing vertically upwards. The door is normally hinged in the outer casing and has a gasket enabling for an air tight closing of the compartment. The hinges are designed to hold the door in an open position when needed. Alternately, the door is held in this position by other means. Moreover, lights means are normally mounted on the lid or the inner case and activated when the door is opened. The light means enables for the user to see down into the compartment. Chest freezer also has baskets hanged resting on the upper horizontal side of the inner and outer cases. These baskets are detachable and can be moved along said upper side.
In order to provide the right amount of cooling air to the compartment a control system is used. This system contains means to receive measured data of temperature, cooling system conditions and operation values adjusted by the user. Using these, the system operates the compressor and cooling system valves in such a way to achieve the best operational conditions. The compressor is then operated so that the cooling agent provides the right amount of cooling energy to the compartment in order to achieve a proper freezer temperature.
One major problem with these kinds of static cooling systems is that the static chest freezer systems tend to create a lot of frost ice on the compartment wall sides. Moreover, the static chest freezer systems are not very good at achieving an even temperature throughout the whole compartment. Another problem is that the heat transfer is not very efficient from the evaporator tubes to the compartment meaning that more energy is needed in order to provide a proper freezer temperature. A further problem is that the arrangement of the evaporator often causes problems during manufacture and use since the tube has to be in direct contact with the inner metal case.
EPO patent publication EP0881441A shows a system for providing cooling energy into freezer and refrigerator compartments. The cooling system is of a dynamic kind and has a fan unit which provides cooling energy throughout the compartments. The refrigerated air is generated by the evaporator and circulated by a fan that drives air through said evaporator. Portions of said air is guided into different direction in order to provide refrigerated air into different parts of the cabinet.
The above-mentioned dynamic cooling system is designed for a refrigerator and freezer compartment. Dynamic systems likes this are commonly used especially for cooling standing cabinets. Ducts of different kinds and baffles are then used in order to guide the air in a proper way. There are different patent applications that suggest ways of implementing dynamic cooling systems into cabinets.
The dynamic systems have a lot of benefits in order to solve the above-mentioned problems. Since the air is circulated around the cabinet, the moisturized and heated air is removed from the cabinet, which avoids frost ice to be collected on the compartment walls and floor. Moreover; the cooling system can be compacted, making it easier and cheaper to implement and produce. Another benefit is that the heat transfer works much better since flowing air gets in direct connect with the foodstuff stored in the compartment.
It is an object of the present invention to provide a cooling system for a Chest freezer which enables a frost-free compartment and also improves the heat transfer between the cooling system and the foodstuff. Moreover, it is an object of the present invention to provide a cooling system for a chest freezer which is easy to implement into an ordinary chest freezer compartment for production.